Control arrangement for a cooling circuit of an internal combustion engine

ABSTRACT

In a control arrangement for the flow of a coolant of a cooling circuit of an internal combustion engine having a radiator for cooling the coolant, a pump for pumping the coolant through the cooling circuit and a control element for controlling the flow of the coolant and wherein a radiator circuit including the engine, the coolant pump and the radiator and a short circuit by-passing the radiator are provided, the control element includes flow control means for selectively establishing a flow circuit through either one or both of the radiator and radiator by-pass flow circuits and also for blocking both the radiator and radiator by-pass flow circuits providing for rapid engine warm-up.

[0001] This is a continuation-in-part application of international application PCT/EP99/07145 filed Sep. 25, 1999 and claiming the priority of German application 198 49 492.0 filed Oct. 27, 1998.

BACKGROUND OF THE INVENTION

[0002] The invention relates to a control device for a cooling circuit of an internal combustion engine of the type which includes a radiator, a coolant pump and a cooling circuit including the radiator and the internal combustion engine.

[0003] A control device of the general type with which the present invention is concerned is known from U.S. Pat. No. 4,644,909. However, this control device is not capable of assuming all the position required to control the cooling circuit of an internal combustion engine.

[0004] DE 43 24 749 A1 describes a regulating valve in which an inlet can be connected to up to three outlets by means of a rotary valve. The inlet is mounted radially on the circumferential wall of the valve housing. This however can lead to considerable problems with installation space in various applications. Moreover, this arrangement results in sealing problems, which are overcome only by a complex and expensive design.

[0005] To control a cooling circuit in an internal combustion engine, thermostatic valves are provided which control a short circuit by-passing the radiator depending on the coolant temperature during the warm-up phase of the internal combustion engine. Then, when the internal combustion engine has sufficiently warmed up, a mixed-mode of operation is initiated during a transition period wherein some of the coolant continues to be conducted through the short circuit and some of it is already passed through a radiator. In the subsequent normal operation, the coolant is generally conducted completely through the radiator of the cooling circuit. In this connection, DE 44 38 552 C1, DE 44 38 237 C1, and DE 42 31 649 C2 are mentioned by way of example.

[0006] However, the known thermostatic valves respond very slowly to temperature changes. Moreover, they are limited to one controlled variable, namely a particular opening temperature. Furthermore, they suffer from high pressure losses for the coolant flowing therethrough.

[0007] DE 41 25 366 C1 discloses a 3/2-way valve for liquid flow circuits in vehicles. This valve has an axial inlet and two radial outlets. The above-mentioned valve serves as a distributor valve or mixing valve in a liquid circuit used to heat space in motor vehicles and is also used in a liquid flow circuit for cooling spaces in motor vehicles. Moreover, mixed-mode operation between heating and cooling is also possible with this valve.

[0008] It is the object of the present invention to provide a control arrangement with a valve, which requires only little installation space and is essentially free of sealing problems. Furthermore, it should be capable of fulfilling all the requirements for controlling the cooling circuit of an internal combustion engine for efficient and non-polluting engine operation.

SUMMARY OF THE INVENTION

[0009] In a control arrangement for the flow of a coolant of a cooling circuit of an internal combustion engine having a radiator for cooling the coolant, a pump for pumping the coolant through the cooling circuit and a control element for controlling the flow of the coolant and wherein a radiator circuit including the engine, the coolant pump and the radiator and a short circuit by-passing the radiator are provided, the control element includes flow control means for selectively establishing a flow circuit through either one or both of the radiator and radiator by-pass flow circuits and also for blocking both the radiator and radiator by-pass flow circuits providing for rapid engine warm-up.

[0010] Since with the arrangement according to the invention, both the flow passage to the radiator circuit and the flow passage to the short circuit can be simultaneously closed by the rotary valve, there is a valve position available, in which no cooling water is permitted to flow through the internal combustion engine. As a result, the cooling water within the internal combustion engine is heated much more rapidly.

[0011] Another very significant advantage of the solution according to the invention is that a significant reduction in cold-starting emissions can be achieved by closing all the coolant flow circuits during cold starting and during the warm-up period of the internal combustion engine. As a result of the complete interruption of the coolant flow, not even the water in the cooling jacket of the internal combustion engine is circulated. The internal combustion engine will therefore warm up very quickly and cold-start emissions, especially hydrocarbon emissions will be greatly reduced.

[0012] The position of the control valve is controlled on the basis of a performance graph by appropriate means providing for an optimum coolant temperature for every engine operating state. This likewise helps to reduce wear of the internal combustion engine and also to reduce fuel consumption. Furthermore, the pressure losses of the coolant in the cooling circuit are reduced which allows a corresponding reduction in the driving power for operating the coolant pump, which also has a positive effect on fuel consumption.

[0013] A further reduction in auxiliary power requirements and therefore in fuel consumption and hence a reduction in emissions is achieved by a cooling water inlet flow restriction when the demand for cooling water is very low and the control valve upstream of the water pump is in a corresponding restrictive position.

[0014] The control valve according to the invention can be disposed at any point in the cooling circuit. It can be incorporated advantageously into the coolant pump, for example, preferably into the suction port of the pump, or into the radiator. It can also be arranged in, or on, the timing belt or chain casing of the internal combustion engine.

[0015] Advantages of the invention will become readily apparent from the description of an exemplary embodiment on the basis of the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016]FIG. 1 shows a cooling circuit with the control device according to the invention in a cold start and warm-up state wherein all the cooling water flow circuits are closed,

[0017]FIG. 2 shows the cooling circuit according to FIG. 1 in an engine warm-up state, wherein the by-pass coolant flow circuit short circuiting the radiator fully open,

[0018]FIG. 3 shows the cooling circuit according to FIG. 1 in mixed-mode operation with coolant flow through the short circuit and the radiator circuit,

[0019]FIG. 4 shows the cooling circuit according to FIG. 1 with the radiator circuit completely open, and the short circuit closed,

[0020]FIG. 5 shows a simplified embodiment of the control valve according to the invention as a control element in the position for cold starting in accordance with the cooling circuit shown in FIG. 1,

[0021]FIG. 6 shows the control valve according to FIG. 5 in the engine warm-up position in accordance with the cooling circuit shown in FIG. 2,

[0022]FIG. 7 shows the control valve according to FIG. 5 in the mixed-mode position in accordance with the cooling circuit shown in FIG. 3, and

[0023]FIG. 8 shows the control valve according to FIG. 5 in the position for maximum cooling in accordance with the circuit shown in FIG. 4.

DESCRIPTION OF PREFERRED EMBODIMENTS

[0024] The cooling circuit illustrated in FIGS. 1 to 4 is of a fundamentally known type, for which reason a more detailed discussion will be restricted below to those components and coolant flow arrangements that are significant for the invention.

[0025] An internal combustion engine 1 cooled by a cooling water circuit is connected to a radiator circuit 2, in which there is a radiator 3 as a heat exchanger, and to a short circuit by-passing the radiator 3. At a point of entry of the short circuit 4 to the radiator circuit 2, there is a control valve 5 as a control element for controlling the coolant flow in the cooling circuit. Between the internal combustion engine 1 and the control valve 5, there is a coolant pump 6, which is used to circulate the coolant through the engine 1.

[0026] Branching off from the radiator circuit 2 is a heating circuit 7, in which there is a heat control valve 8, a heater 9 and a pump 10. The heating circuit 7 leads to the inlet side of the coolant pump 6 downstream of the control valve 5.

[0027] The configuration chosen for the control valve 5 should be one that allows four positions, namely a total shut-off position (FIG. 1), a position in which the coolant, generally water, is passed exclusively via the short circuit (FIG. 2), a position in which the coolant is passed exclusively via the radiator circuit 2 (FIG. 4) and another position, in which mixed-mode operation, i.e. partial opening of the short circuit 4 and of the radiator circuit 2, is possible (FIG. 3).

[0028]FIG. 1 shows the cooling circuit, in which the control valve 5 is in a total shut-off position, with the result that both the short circuit 4 and the radiator circuit 2 are closed. To prevent circulation of the coolant in the water jacket of the internal combustion engine 1, it should of course be ensured that the regulating valve 8 for the heating circuit 7 is likewise closed.

[0029] In this position, there is flow restriction at the inlet of the coolant pump 6 and energy consumption is correspondingly reduced at the coolant pump 6 is designed for operation with restricted inlet flow.

[0030] According to the circuit configuration shown in FIG. 2, the control valve 5 is in a position in which the radiator circuit 2 is shut off, but the short circuit 4 by passing the radiator 3 is open.

[0031] With the setting according to FIG. 3, mixed-mode cooling water flow operation is made possible by appropriate positioning of the control valve 5, there being partial cooling water flows through the short circuit 4 and through the radiator circuit 2.

[0032]FIG. 4 represents the circuit configuration in all the cooling water of the internal combustion engine 1 flows through the radiator circuit as it occurs during normal engine operation, the short circuit 4 being fully closed.

[0033] If required, a control device (not shown) can be used to ensure that the flow of coolant through the internal combustion engine 1 is interrupted.

[0034] In the positions shown in FIGS. 2 to 4, the seat control valve 8 can be opened partially or fully to heat the interior of the vehicle's passenger compartment.

[0035] The control valve 5 can be operated in any desired manner, e.g. by electric motor 5′. If operated by an electric motor, the valve can be controlled for any desired position. For optimum operation, a control valve will be provided for this purpose, with control variables being provided by an engine performance graph.

[0036] To avoid damage to the internal combustion engine if a fault occurs in the cooling circuit, e.g. if the drive for the control valve fails, which could be caused by failure of the power supply, the arrangement could be such that the radiator circuit 2 is opened in such an emergency situation. This can be achieved in a simple manner, e.g. by employing an appropriate spring return system to ensure that the control valve 5 is moved to a position in which the radiator circuit 2 is opened whenever a failure occurs.

[0037] FIGS. 5 to 8 illustrate the principle on which a control valve 5, is based purely in an exemplary manner. As can be seen, the control valve 5 is designed in such a way that it has a rotary spool 11 in the form of a sleeve, which is arranged in a cylindrical valve housing 12 so as to be rotatable about its longitudinal axis. The rotary spool 11 is provided with an axial common flow connection 13 at one end while being closed at the other end. At the closed end, the spool is provided with a driving device (not shown) for rotating the spool about its longitudinal axis. The valve housing 12 is likewise closed at the end remote from the driving device (not shown).

[0038] The rotary spool 11 has a control opening 14 in its circumferential wall. In the embodiment selected, the valve spool 11 has a cylindrical wall with a control opening 14 and extends circumferentially over an angle of more than 180°, preferably about 190 to 200°.

[0039] In its cylindrical circumferential wall, the valve housing 12 has an opening for a connection 15 to the short circuit 4 and a connection 16 to the radiator circuit 2. In the exemplary embodiment illustrated, the connections 15 and 16 each represent inlets, while the common connection 13 forms the outlet connected to the coolant pump.

[0040]FIG. 5 shows the position of the rotary spool 11 in which, as shown in FIG. 1, both the radiator circuit 2 and the short circuit 4 are closed.

[0041]FIG. 6 shows the position of the rotary spool 11 in which, in accordance with the circuit arrangement shown in FIG. 2, the coolant circulates through the short circuit 4. Here, the position of the rotary spool 11 is chosen in such a way that the connection 15 is completely open. In accordance with the exemplary embodiment, however, a partial opening with correspondingly restricted circulation of the coolant through the short circuit 4 is also possible. This makes it possible to provide for very sensitive flow control with a continuous manner from a shut-off position in accordance with FIG. 5 to a completely open position as shown in FIG. 6.

[0042]FIG. 7 shows mixed-mode operation with coolant flow both through the short circuit 4 and also through the radiator circuit 2. Here too, intermediate positions with different flow rates through the radiator circuit 2 and the short circuit 4 can be selected.

[0043]FIG. 8 shows a cooling circuit with a cooling water flow exclusively through the radiator circuit 2. The short circuit 4 is closed. Here too, restricted operation via the radiator circuit 2 by means of a corresponding intermediate position of the rotary slide 11 with partial opening of the connection 16 is possible.

[0044] Various embodiments for the control valve 5 may be provided. Thus, for example, a rotary spool 11 with axial, semi-axial and/or radial branches or connections are possible. It is likewise possible to use a control valve other than a rotary spool valve 11.

[0045] The illustrated position of the control valve 5 on the inlet side of the coolant pump 6 as shown in the drawings also represents only one possible arrangement. The valve may also be disposed at the delivery side of the coolant pump 6, between the latter and the internal combustion engine. In this case, the axial common connection 13 could act as an inlet to the control valve 5 and the connections 15 and 16 would then control the discharge of the coolant to the radiator circuit 2 and the short circuit 4, respectively. 

What is claimed is:
 1. A control arrangement for the coolant flow of a cooling circuit of an internal combustion engine, having a radiator with a coolant pump for pumping the coolant through said coolant circuit and a control element for controlling the flow of coolant through the cooling circuit, said cooling circuit including a radiator circuit which includes the internal combustion engine, the coolant pump and the radiator, and a short circuit, which includes only the internal combustion engine and the coolant pump, said control element comprising a control valve arranged in said cooling circuit and having respective connections for said radiator circuit and said short circuit, and a common connection for said internal combustion engine and said pump, said control valve including a valve element having selectivity a shut-off position for said radiator circuit and said short circuit, a position providing, selectively, a connection between the radiator circuit or the short circuit and the common connection or a connection of the radiator circuit and the short circuit by-passing the radiator to the common connection for a mixed-mode operation and a position in which both connections for the radiator circuit as well as the short circuit are simultaneously closed by said valve element.
 2. A control arrangement according to claim 1 , wherein said valve element is operated by an electric motor.
 3. A control arrangement according to claim 1 , wherein said valve element is a rotary spool valve.
 4. A control arrangement according to claim 3 , wherein said spool valve has a cylindrical wall and a central axial opening and said connections for said radiator circuit and said short circuit are provided in the circumferential wall and are inlets and said common connection is provided for said central axial opening.
 5. A control arrangement according to claim 1 , wherein said cooling circuit includes a heating circuit and said heating circuit includes a switching device for interrupting the flow of coolant therethrough.
 6. A control arrangement according to claim 1 , wherein said control valve is disposed at the inlet region of said coolant pump.
 7. A control arrangement according to claim 1 , wherein said control valve has a rest position which is assumed by said control valve during an emergency whereby said valve is automatically moved to a position in which a coolant flow connection is established through said radiator circuit. 